HEDTA and various other nitrilopolycarboxylates such as nitrilotriacetates (NTA) and ethylenediaminetetracetates (EDTA) have been used as detergent additives for various purposes. For example, British Patent Specification 818,151 published Aug. 12, 1959, a patent of addition to British patent specification No. 716,574, discloses mixtures of alkali metal phosphates with salts of polycarboxylated amines including the sodium salt of hydroxyethyl ethylenediaminetriacetate.
U.S. Pat. No. 2,921,809 issued Jan. 19, 1960 to McCune discloses a detergent composition containing sodium alkylbenzene sulfonate, the sodium salt of hydroxyethylethylenediaminetriacetate (HEDTA) and a phosphated alkyl polyethylene glycol corrosion inhibitor.
U.S. Pat. No. 3,591,405 issued July 6, 1971, to McCarty discloses rinse-added fabric softener compositions containing 4-50% of a quaternary ammonium compound, 25-94% of a polyphosphonate, an optical brightener and 0-31% of a polyacetate sequestering agent. Suitable polyacetates are identitied as including EDTA, NTA, and HEDTA.
U.S. Pat. No. 3,151,084 issued Sept. 29, 1964, to Schiltz et al. discloses alkylbenzenesulfonate-containing detergent compositions in which solubility is said to be improved by the addition of 0.25-4% of a mixture of EDTA and another amino solubilizing agent selected from salts of N,N-di(2-hydroxyethyl)glycine, iminodiacetic acid, NTA and HEDTA.
U.S. Pat. No. 3,970,596 issued July 20, 1976, to Klish et al., discloses 0.1-0.2% HEDTA in liquid dishwashing compositions containing no other detergent builder components.
U.S. Pat. No. 3,920,564 issued Nov. 18, 1975, to Greciek discloses softener/detergent compositions containing surfactants, quaternary ammonium or diamine fabric softeners and a builder salt selected from aminocarboxylates, citrate and mixtures. Example IV replaces 35% NTA in prior examples with 35% HEDTA.
U.S. Pat. No. 3,899,477 issued Aug. 12, 1975, to McDonald, discloses aqueous detergent compositions containing anionic surfactants and a colloidal silica sol formed in situ. Example IV compositions contain HEDTA.
British Pat. No. 1,513,550 issued to Hampson published June 7, 1978, discloses dishwashing detergent compositions containing surfactants, 0.5-30% of a magnesium salt and 3-60% of an organic sequestering agent having a pK value for calcium of at least 3 and a difference between the pK value for calcium and magnesium of at least 0.5. A number of hydroxyalkyl-substituted chelating agents are disclosed.
U.S. Pat. No. 4,397,776 issued Aug. 3, 1983, to Ward, discloses liquid detergent compositions containing 0.005%-40% alpha amine oxide C.sub.12-18 carboxylates and 0.001%-35% chelating agents. Example 11-B discloses a composition containing HEDTA.
None of these references disclose the compositions of the present invention or recognize the unique fabric stain removal properties of HEDTA or related compounds in the context of laundry detergent compounds containing no or low levels of inorganic phosphate detergency builders.